Projects : Hawaiian Koʻa (Coral) Card

OverviewHow to ParticipateGet Your CardSubmit ObservationsMap ViewerAcknowledgements


Climate Change Impacts on Coral Reefs

Carbon released through human activity is changing ocean chemistry and increasing temperatures globally. Higher than usual ocean temperatures have led to to an increase in coral bleaching events and their severity. So what is coral bleaching? Corals are animals that house photosynthetic algae, called zooxanthellae. These give corals their colors and provide most of the energy they require. Coral bleaching is a stress response that results in the loss of zooxanthellae, revealing the white skeleton. If stressful conditions persist, corals do not get the energy they require and will die. Widespread coral bleaching events have impacted nearly every coral reef region in the world and are directly linked to increasing sea water temperatures due to climate change.

Get Involved!

The Hawaiian Koʻa (Coral) Card was developed by researchers from the Hawaiʻi Institute of Marine Biology’s Coral Reef Ecology Lab to help determine the health and bleaching status of Hawaiʻi’s coral reefs based on actual health factors related to each color. The color of corals serves as a health indicator and helps to identify baselines, current conditions, and change over time. The Koʻa Card was designed for use by everyone, including the community, citizen scientists, researchers, students, resource managers, recreational users and visitors.

Snorkeler with Koa Card

Using the Koʻa Card to determine the coral color. Photo Credit: Coral Reef Ecology Lab.


When using these data, please cite the following publication:

Related publication: Bahr, K.D., S.J.L. Severino, A.O. Tsang, et al. 2020. The Hawaiian Koʻa Card: coral health and bleaching assessment color reference card for Hawaiian corals. SN Applied Sciences 2, 1706.

How to Participate

Make a Difference – Help Survey Hawaiʻiʻs Coral Reefs

Become a citizen scientist! You don’t need to be an expert to participate. The next time you are out snorkeling or diving, bring along a coral color card to identify the color of coral colonies, as well as their shape. Submit your observations along with your survey location(s) online. Your efforts will help identify areas of bleaching and areas of resilience throughout the State of Hawaiʻi. Follow these 4 basic steps when surveying:

1. Suggested Survey Methods

The following three survey methods are suggestions and can be used when diving, snorkeling, or wading. You are also welcome to use any other unbiased surveying method. Choose a monitoring method that suits your skills, experience, and location.

  1. Transect Method — Survey 10 corals along a 30 foot transect line, recording coral information every 3 feet along the line.
  2. Haphazard Method — Survey 20 individual coral colonies chosen randomly. In order to prevent bias, some tips to help randomize your selection may include pre-determining your bearings, establishing distance between coral selection, or closing your eyes and swimming a certain number of fin kicks before opening your eyes and selecting the first coral you observe.
  3. Repetition Method — Return to the same coral colony over time.

Here are a few more useful tips while using the Koʻa Card:

  • Monitor at least 20 corals per survey.
  • Estimate the bleaching in the area (e.g., 0-10%).
  • Color is lost with depth. Use a light when diving below 5m/15ft.
  • When available, use a GPS to record coordinates.
  • If you have an underwater camera, take a photo! This can be submitted along with your observations.
  • Coral are fragile animals, please do not touch or step on corals.

2. Coral Shape

Knowledge of coral species is not required in order to use the Koʻa Card assessment tool. Just a general understanding of coral morphology is sufficient. There will be four different shapes to select from:

Coral shapes

3. Coral Color

Select the color that best represents the whole colony! A coral colony is not always one uniform color, branched tips are usually lighter in color.

Coral color

4. Report Data

Itʻs easy! Check out the submission form. You can select your survey location on the map in order to retrieve GPS coordinates. Provide all your other survey information and submit! All submitted data can be viewed on the Map Viewer.

Check out This Training Video

Get Your Card

To get you started, pick up your Koʻa Card today. If the pick-up locations listed below are not accessible to you, please contact if you would like to make other arrangements to pick up a Koʻa Card!

Koa card


  • Division of Aquatic Resources Office, 3060 ʻEiwa Street, Room 306 Līhuʻe, HI 96766 (808.274.3344)
  • Limahuli Garden and Preserve, 5-8291 Kuhio Hwy, Hanalei, HI 96714 (please contact Sari Pastore | 808.826.1053)


  • Division of Aquatic Resources Office, 1151 Punchbowl Street, Room 330 Honolulu, HI 96813 (808.587.0100)
  • Aaron’s Dive Shop, 307 Hahani St, Kailua, HI 96734 (808.262.2333)
  • PacIOOS Office, 1680 East-West Road, POST 815, Honolulu HI 96822 ( | 808.956.8784)


  • Division of Aquatic Resources Office, 101 Māʻalaea Boat Harbor Road Wailuku, HI 96793 (808.243.5294)

Hawaiʻi Island

  • Division of Aquatic Resources Office, 74-380B Kealakehe Parkway Kailua-Kona, HI 96740 (808.327.6226)
  • Division of Aquatic Resources Office, 75 Aupuni Street, Room 204 Hilo, HI 96720 (808.961.9530)
  • Mokupāpapa Discovery Center, 76 Kamehameha Ave, Hilo, HI 96720 (808.933.8180)

Submit Observations

Please follow the link below to submit detailed information from your reef survey and observations. If you have an accompanying photo, we encourage you to submit it along with your entry. Mahalo for your participation!

data submission tool screenshot

Map Viewer

Please follow the link below to view all submitted reef observations in an interactive map viewer. Zoom into your area of interest and explore how fellow citizen scientists have contributed to this effort.

map viewer screenshot


Harold Castle Foundation logo Hawaii Community Foundation logo Condit logo
Coral Reef Ecology Lab logo HIMB logo Sea Grant logo PacIOOS logo
Harold Castle Foundation logo Hawaii Community Foundation logo
Condit logo Coral Reef Ecology Lab, HIMB logo
HIMB logo Sea Grant
PacIOOS logo

The development of this online submission tool and map viewer was made possible by leveraging work conducted for a grant/cooperative agreement from the U.S. Geological Survey, National Climate Adaptation Science Center to the Pacific Islands Climate Adaptation Science Center at the University of Hawaiʻi at Mānoa and the National Oceanic and Atmospheric Administration, Project A/AS-1, which is sponsored by the University of Hawaiʻi Sea Grant College Program, SOEST, under Institutional Grant No. NA18OAR4170076 from NOAA Office of Sea Grant, Department of Commerce. The views expressed herein are those of the author(s) and do not necessarily reflect the views of USGS, NOAA or any of its subagencies. UNIHI-SEAGRANT-II-18-01.